feat: implement 3-tier sniper strategy with weighted sizing

- Replace single price/shares with 3-tier system (3c/2c/1c)
- Tier allocation: 20%/30%/50% (high→low price)
- Min 5 shares per tier enforced
- Update .env.example with new config vars
- Update README.md with strategy documentation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.env.example

@@ -135,18 +135,22 @@ MM_ADAPTIVE_MONITOR_SEC=5
 
 # ─────────────────────────────────────────────
 # ORDERBOOK SNIPER (sniper.js / npm run sniper-sim)
-# Places tiny GTC BUY orders at a low price on both sides of
-# ETH/SOL/XRP 5-minute markets — catches panic dumps near $0.
+# 3-Tier Strategy: Places GTC BUY orders at 3 prices with weighted sizing
+# Tier 1 (3c): smallest size | Tier 2 (2c): medium | Tier 3 (1c): largest
+# Catches panic dumps at multiple price levels with optimal capital allocation
 # ─────────────────────────────────────────────
 # Comma-separated assets to snipe
 SNIPER_ASSETS=eth,sol,xrp
 
-# Buy price per share (1 cent = $0.01)
-SNIPER_PRICE=0.01
+# 3-Tier pricing (high to low)
+SNIPER_TIER1_PRICE=0.03  # Highest price, smallest allocation (20%)
+SNIPER_TIER2_PRICE=0.02  # Mid price, medium allocation (30%)
+SNIPER_TIER3_PRICE=0.01  # Lowest price, largest allocation (50%)
 
-# Shares per side — minimum Polymarket order size is 5 shares
-# At $0.01/share: 5 shares = $0.05 per side, $0.10 per market
-SNIPER_SHARES=5
+# Max total shares per side (min 5 shares per tier)
+# Example: 15 shares → 3@3c + 5@2c + 7@1c
+# Example: 30 shares → 6@3c + 9@2c + 15@1c
+SNIPER_MAX_SHARES=15
 
 # ── Sniper Session Schedule (all times UTC+8) ──────────────
 # Format: HH:MM-HH:MM,HH:MM-HH:MM (comma-separated sessions)